Every winter there is a topic about how to spot aurora borealis.
Finnish meteorological institute has established a site called AURORAS now! to help in this quest.
From the site you can find diagrams like below showing sun-activity during last 24+ hours. You can also join to mailing list which alerts if the probability is high enough to see something. (Daytime values peaking above 30)
Graph of current 24h cycle near Rovaniemi provided by FMI